The present disclosure relates to batteries and, more particularly, to a terminal assembly for measuring current flow to and from a post of a battery. Even more particularly, the present disclosure relates to a battery incorporating a terminal assembly for measuring current flow to and from a post of the battery.
The present disclosure is described in conjunction with a lead-acid battery of the type used to provide starting power for the internal combustion engine in vehicles, such as automobiles, trucks and motorcycles and or motive power for electric and hybrid-electric vehicles. This type of battery generally includes a plastic casing containing positive and negative lead plates immersed in an acid electrolyte. The plates are separated by nonconductive sheets, and a positive lead strap connects the positive plates while a negative lead strap connects the negative plates. Lead posts are connected to each strap and extend through the casing, and lead positive and negative battery terminals are secured to the ends of the posts outside the casing for receiving cable connectors.
In present day vehicle systems there is generally no means to ascertain the status of the battery beyond the alternator output voltage. Presently, means for monitoring the status of batteries normally measures the voltage provided between the battery terminals. However, battery voltage in itself provides limited information as to battery status and performance beyond measurement of open circuit voltage and an estimate of the battery state-of-charge based on the measured open circuit voltage. What is desired instead is an integral intelligent battery which provides means for measuring the flow of current into and out of the battery as well as the battery terminal voltage and battery temperature and contains electronics means to communicate and analyze these battery measures. The measures of current, voltage and temperature can then be used over time to calculate and monitor the level of charge of the battery. The preferred battery design solution would also provide means to incorporate microelectronic circuitry capable of utilizing these measures without adversely impacting the size and utility of the subject battery. The integrated microelectronic circuitry is then utilized to provide analysis and communication of battery performance and remaining capacity based on these measures. Preferably, the terminal assembly and cover assembly will be simple in design, and easily incorporated in a battery within the battery manufacturers current manufacturing capabilities. What is also desired is a battery including an integrated terminal assembly for monitoring the flow of current into and out of the battery.
In response, the present disclosure provides a battery cover assembly which provides the integral means for measuring electrical current passing to and from a battery post, means to measure the battery terminal voltage as well as means to integrate electronic circuitry within the existing physical envelope of the battery. The battery cover assembly further incorporates at least one terminal assembly for the measurement of current flow. The terminal assembly includes an electrically conductive collar having an inner surface for connecting to a battery post and an outer surface, and an electrically conductive terminal having an outer surface for receiving a cable connector, for example, of a vehicle. The assembly also includes an electrically conductive resistor having a known resistance extending between the outer surfaces of the collar and the terminal. Current flow from the battery post travels through the resistor from the collar to the terminal and current flow to the post travels through the resistor from the terminal to the collar.
According to one aspect, the resistor of the terminal assembly is made from a metallic alloy material including manganese, nickel and copper, which provides a very low temperature coefficient of resistivity.
The present disclosure also provides a battery post cover for receipt on a battery having at least one battery post extending therefrom. The cover includes the terminal assembly discussed above and further includes a first surface having a terminal port, a second surface having a post port, and wherein the cover defines a closed chamber. A circuit board is received in the closed chamber, and the terminal assembly is received in the cover with the terminal extending out of the terminal port and the collar positioned in the post port for receiving a battery post. Leads extend from the outer surfaces of the terminal and the collar of the terminal assembly into the closed chamber of the cover, and are electrically connected to the circuit board. These leads further provide the means to mechanically secure the circuit board to the cover as well as provide the electrical connections to the current sensing resistor and the opposing polarity battery terminal to measure battery terminal voltage.
According to one aspect of the present disclosure, a voltage measuring means is mounted on the circuit board and connected between the first and the second leads of the terminal assembly for measuring the voltage drop across the resistor.
According to another aspect of the present disclosure, a voltage measuring means is mounted on the circuit board and connected between the first leads of the terminal assembly and the leads of the opposing polarity battery terminal for measuring the voltage potential across the battery terminals.
According to another aspect, a computer is also mounted on the circuit board. The computer has memory storing the known resistance of the resistor, and a processor programmed to receive the measured voltage drop from the voltage measuring means, retrieve the known resistance from the memory, and calculate current flow through the resistor based on the measured voltage drop and the known resistance.
According to a further aspect, the battery post cover includes a thermometer for measuring an actual temperature of the resistor, and the memory of the computer also stores a temperature coefficient of resistivity for the resistor. In addition, the processor is programmed to receive the actual temperature from the thermometer, retrieve the temperature coefficient of resistivity from the memory, calculate an actual resistance of the resistor based on the known resistance, the temperature coefficient of resistivity, and the actual temperature, and calculate actual current flow through the resistor based on the measured voltage drop and the actual resistance.
The present disclosure also provides a battery including the battery post cover, and further including a case, a storage cell contained within the case for receiving and storing an electrical charge, and an electrically conductive post connected to the storage cell and extending out of the case. The post extends into the post port of the cover and is received by the collar of the terminal assembly.
According to one aspect of the present disclosure, the storage cell of the battery includes lead and lead-oxide plates immersed in an acid electrolyte.
These and other aspects of the present disclosure will become apparent to those skilled in the art after a reading of the following description of the preferred embodiment when considered with the drawings.